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Vastus lateralis muscle

The vastus lateralis is the largest and most powerful component of the quadriceps femoris group. It forms the bulk of the anterolateral thigh and plays a key role in knee extension. Its large superficial belly is an important landmark in orthopedic and sports medicine. It is commonly involved in sports-related injuries, postoperative weakness, and is frequently used as a donor site for muscle flaps in reconstructive surgery.

Synonyms

  • Vastus externus

  • Lateral quadriceps muscle

  • Lateral vastus of thigh

Origin, Course, and Insertion

  • Origin:

    • Arises from the greater trochanter, intertrochanteric line, lateral lip of the gluteal tuberosity, and the lateral lip of the linea aspera of the femur

  • Course:

    • Fibers descend vertically down the anterolateral thigh

    • The muscle belly forms the lateral margin of the quadriceps femoris group and is partially covered by the iliotibial tract

    • Its fibers converge into a broad aponeurosis that forms part of the quadriceps tendon

  • Insertion:

    • Inserts via the quadriceps tendon into the patella, and continues as the patellar ligament to attach to the tibial tuberosity

Relations

  • Anteriorly: Fascia lata, iliotibial tract, subcutaneous tissue

  • Posteriorly: Vastus intermedius, femur

  • Medially: Rectus femoris, vastus intermedius

  • Laterally: Iliotibial tract and biceps femoris (proximal thigh)

Nerve Supply

  • Femoral nerve (L2–L4)

Arterial Supply

  • Lateral circumflex femoral artery (descending branch)

  • Perforating branches of the profunda femoris artery

  • Superior lateral genicular artery (distal portion)

Venous Drainage

  • Drains into lateral circumflex femoral vein and profunda femoris vein, ultimately into the femoral vein

Function

  • Primary extensor of the knee joint

  • Provides lateral stability to the patella by counteracting medial pull of vastus medialis

  • Assists in maintaining posture during standing and gait

  • Contributes to forceful knee extension in running, jumping, and climbing

Clinical Significance

  • Frequently involved in quadriceps strains and tears

  • Important donor muscle for myocutaneous flaps in reconstructive surgery

  • Weakness or atrophy affects patellar tracking and predisposes to anterior knee pain

  • Hypertrophy or imbalance may contribute to patellofemoral malalignment

MRI Appearance

T1-weighted images:

  • Muscle shows low-to-intermediate signal intensity

  • Chronic fatty infiltration or degeneration appears bright

T2-weighted images:

  • Baseline signal is low-to-intermediate

  • Edema, tear, or acute strain demonstrates bright signal intensity

STIR (Short Tau Inversion Recovery):

  • Normal signal is low-to-intermediate

  • Acute injury, inflammation, or myositis shows bright signal intensity

Proton Density Fat-Sat (PD FS):

  • Low-to-intermediate baseline signal

  • Pathological areas show bright signal intensity, especially at myotendinous junction

T1 Fat-Sat Post-Contrast:

  • Normal muscle shows mild uniform enhancement

  • Pathology shows heterogeneous enhancement; abscess shows rim enhancement

CT Appearance

Non-Contrast CT:

  • Appears as homogeneous soft tissue density along lateral thigh

  • Hematomas appear hyperdense acutely

  • Chronic fatty degeneration shows as low attenuation areas

Post-Contrast CT:

  • Muscle enhances mildly and evenly in normal state

  • Inflammatory or neoplastic lesions show stronger and irregular enhancement

  • Abscess appears as central low density with peripheral rim enhancement

MRI image

Vastus lateralis muscle mri axial anatomy image-img-00000-00000

MRI image

Vastus lateralis muscle mri axial anatomy image-img-00000-00000_00001

MRI image

Vastus lateralis muscle mri axial anatomy image-img-00000-00000_00002

CT image

Vastus lateralis muscle

CT image

Vastus lateralis muscle ct coronal

MRI image

Vastus lateralis muscle coronal cross sectional anatomy 3T radiology anatomy image-img-00000-00000

MRI image

Vastus lateralis muscle sagittal cross sectional anatomy 3T radiology anatomy image-img-00000-00000